1. Field of the Invention
The invention relates to a novel charge sensitive preamplifier without a physical resistor in parallel with a capacitor in a feedback loop to provide DC stabilization.
2. Description of the Related Art
Charge sensitive preamplifiers (CSPs) are the most commonly used amplifiers for signals delivered by light, radiation and particle detectors. Some examples of these detectors are photodiodes, X-ray detectors and detectors for nuclear and particle physics. The applications of CSPs are in applied research (X-ray spectroscopy in medicine, biology) and in basic research (high energy physics, nuclear physics, astrophysics). When connected to a detector, the CSP gives an output voltage pulse with a maximum amplitude proportional to the amount of the charge delivered by the detector. The precision in the measurement of the electric charge depends on the output noise level of the detector-amplifier system. In spite of the fact that a CSP is inherently a less noisy amplifying configuration, great efforts have been made to reduce the noise level even further. The absence of a resistor in parallel with a capacitor in a feedback loop would reduce the noise level of the preamplifier. However in the prior art the configuration without a resistor requires a complicated reset circuitry and is limited to very low values of the leakage current.